Recorder ballpoint pen



Nov. 2, 1965 [1.1. NEvlLLE ETAL 3,215,121

RECORDER BALLFOINT PEN Filed March l5, 1964 E MMM Arran/n United States Patent O 3,215,121 RECORDER BALLPOINT PEN Dee J. Neville, Gardena, and Arthur .1. Spar-ling, Manhattan Beach, Calif., assignors to Telautograph Corporation, Los Angeles, Calif., a corporation of Virginia Filed Mar. 13, 1964, Ser. No. 351,688 7 Claims. (Cl. 1Z0-42.06)

This invention relates to ballpoint pens and, more particularly, to a ballpoint pen for use in automatic recording machines and the like.

In automatic recording machines, remote writing devices and the like, a writing stylus is moved mechanically across a sheet of paper. It is desired that a dense legible line be providedon the paper without undue leakage' of the writing fluid used with the stylus. Leakage creates a line which is wider than desired with the result that small squiggles in the line traced by the stylus are not intelligible. A ballpoint stylus is preferred in automatic recording machines for two primary reasons: the writing liuids used with such styli are extremely dense and viscous resulting in a great reduction in the quantity of ink required, also the ballpoint stylus has the capability of writing multiforrn carbons. Wet ink systems are inherently messy because ink is thrown or leaks from the stylus. This invention enhances the potential for cleanliness of the standard ballpoint ink.

It has been a problem, in the past, to obtain adequately dense lines from a ballpoint stylus where such is used in mechanically operated writing devices without also encountering problems of ink leakage. In such devices the force with which the ball is engaged with the paper is limited and is usually considerably smaller than the force normally encountered in the use of manually held ballpoint pens. The ball ina ballpoint recording stylus, therefore, must be loosely engaged in its holding sleeve in order to provide a sufficiently dense line.

This loose fit, however, causes an excess amount of ink to flow past the ball with the result that ink accumulates on the point end and an uneven line is laid down having globs of excess ink at the tip of loops or points where the pen c-hanges direction. Also the excess ink tends to accumulate on the paper hold-down frame. If the fit of the ball with its sleeve is made tighter to reduce ink leakage, a weak line is laid down because ink is not properly fed to the ball.

Moreover, a ballpoint recording stylus must be selfstarting after long periods of non-use. This requirement can be met by the use of low viscosity ink. After the pen starts, however, the low viscosity ink produces excess leakage.

This invention provides an improved ballpoint stylus which is particularly adapted for use in automatic recording machines and the like. The improved stylus provides a dense line on the paper without excessive leakage of ink onto the paper. The stylus is self-starting without excessive leakage. Further, the improved stylus is protected from adverse effects by impact against the frame which holds the paper against the platen.

Generally speaking, this invention provides a writing stylus for a mechanically operated writing device. The stylus comprises a ball support tube adapted at one of its ends to be coupled to a source of viscous ink. A spherical ball is rotatably mounted in the other end of the tube and projects beyond the said other end. The tube denes an ink duct communicating the one end of the tube with the ball. The stylus also includes a cylindrical sleeve disposed in substantially concentric relation to the tube and having an end disposed adjacent the ball. The ball projects beyond the end of the sleeve.

' The above-mentioned and other features of the invention are more clearly set forth in the following detailed explanation of the invention take in conjunction with the accompanying drawings wherein:

FIGURE l is an enlarged cross-sectional elevation view of a ballpoint stylus according to this invention; and

FIGURE 2 is a further enlarged View of the ball and its mounting.

Referring to the drawings, a writing stylus 10 for a mechanically operated writing device is shown. The stylus includes a spherical ball 11, a ball support tube 12, and a sleeve 13. The sleeve, as will be explained, operates to form an auxiliary ink reservoir about the circumference of the tube. Preferably ball 11 is fabricated from a hard carbide material so that its diameter remains substantially unchanged during continued use of the stylus.

The ball support tube 12 is adapted to be coupled, as indicated at 15, to a source 16 of viscous ink. As shown in FIGURE 2, the ball 11 is loosely mounted in a recess 18 in the other end of the tube 12, the ball being rotatable in the recess. The recess has a circular cross-section and the maximum diameter of the recess is slightly greater than the diameter of the ball, providing an annular space 32 which meters the ink iiow. The recess is shaped to define an ink supply chamber 19 behind the ball. The tube is formed into a thin-walled tapered skirt 20 which serves to retain the ball in the recess. The end of the skirt is iiat and so it ilares away from the ball because of the curvature of the ball. The ball projects beyond skirt 20 a distance a (see FIGURE 1). j

The ball support tube 12 has an ink supply duct 21 along its extent between source 16 and the chamber 19. If desired, the tube may be bent, as at 22 in FIGURE 1, to adapt the stylus to -a particular Writing arm or pen holder in a mechanical writing device.

At a location spaced a predetermined distance from the ball end of the tube 12 but not so far as to be around the bend 22, the ball support tube has an enlarged diameter portion 23 having a cylindrical exterior surface.

The sleeve 13 has an inner diameter which corresponds to the diameter of the tube portion 23 in such a way that the sleeve may be shrunk or force fitted to the tube as shown in FIGURE 1. The sleeve extends from the tube portion 23 toward the ball end of the tube 12 to an end 24 so as to be substantially concentric with the tube and spaced from the portion of the tube immediately behind the ball by a distance c. The sleeve end 24 is located in a plane which is normal to the axis of the tube and which is spaced a distance b behind the outermost point of the ball. Preferably, the inner rim of the sleeve at the end 24 is chamfered as shown in FIGURE 1.

The ball skirt 20 is quite thin-walled and usually is about .001 inch thick radially of the ball. The skirt functions to sweep excess ink from the ball back into the chamber 19 in response to rotation of the ball in the recess 18. In order to provide a proper iiow of ink to the ball, a carefully controlled clearance is provided by the metering space 32 between the ball and the skirt.

By providing the sleeve 13 around the outside of the pen, as described, it has been found that the ink leakage problems are greatly improved, a uniformly dense line-of uniform width is laid down, and instant starting of the writing operation after long periods of non-use of the stylus is achieved.

In particular, it has been found that paper bers 30 accumulate in the annular space between the tube and the sleeve to form a matrix in the space. Any excess ink, which formerly would have been troublesome, flows back around the skirt into this space. Ultimately the exuded ink bridges the space, in cooperation with the paper fiber matrix therein, to form an auxiliary ink pool 31 (see FIGUREvl). The pool forms a pronounced rneniscus at the skirt that surrounds and engulfs the ball at the flared extremity of the skirt. The paper fibers create a blotter or sponge-type reservoir for the exuded ink and keep the pool adjacent the ball replenished. The fibers also have the effect of extending the pool farther up the ball from the skirt than is possible by the mechanism of the meniscus alone.

The fiber and ink body in the annular space between the tube and the sleeve provide a self-regulating system. If ink flow past the metering space 32 to the exposed portion of the ball becomes excessive, a phenomenon which normally would produce a blotchy uneven written line, the excess ink is accumulated in the annular space for even redeposition and an unmanageable build-up of ink on the ball does not occur. Moreover, paper fibers cease to accumulate between the tube and the sleeve after an effective ink pool has been formed.

Because of the auxiliary supply of ink surrounding the ball, the stylus is always ready to start, even after protracted periods of non-use; this is an especially valuable feature of the invention in a stylus for mechanical writing devices where limited stylus pressure is available. Additionally, it has been found that the stylus writes effectively on a horizontal or vertical surface. Shocks and vibrations do not cause ink to be thrown from the stylus.

In an automatic writing device it is quite common for the stylus to be rapped sharply against the frame which holds down the paper on the platen, as when the arm which carries the stylus is subjected to shock or vibration. When such occurs, the skirt around the ball may be deformed against the ball so that either excess ink is caused to fiow to the ball, or ink which is not consumed is not returned to chamber 19. The damaged stylus leaks excessively. The sleeve 13, however, in addition to the other advantages which were described above, protects the skirt 20 so that such damage does not occur.

In a presently preferred stylus according to this invention, the carbide ball has a diameter of .039 inch, although balls of from .035 to .045 inch inclusive may be used. The mean annular gap c is .018 inch, although the gap may have a value of from .015 to .O25 inch, inclusive, with .016 to .020 inch, inclusive, being the preferred range of values. The set-back b of sleeve end 24 from the outer end of the ball is .010 inch, although the set-back may beI from .007 to .012 inch inclusive. The above-mentioned ranges of dimensions for distances b and c apply independently of the diameter of ball used. Distance a from the end of the skirt 20 to the exposed extremity of the ball is .010 inch. Distance a is preferably equal to or greater than distance b with b being as small as practical to provide clearance with the writing surface. The ink used in the preferred stylus was Formulabs Photocopy Recorder Blue No. 716 having a viscosity of 2200i10% centipoises. The writing force used with the stylus was substantially 40 grams.

While the invention has been described above in conjunction with specific apparatus, this has been done with respect to a presently preferred device according to the invention yfor the purposes of illustration and description only and is not to be considered as limiting the scope of the invention.

What is claimed is:

1. A writing stylus for a mechanically operated writing device comprising a ball support tube adapted at one end thereof to be coupled to a source of viscous ink, a spherical ball rotatably mounted in the other end of the tube and projecting beyond the tube end, the tube defining an ink duct from the ink source to the surface of the ball, a :sleeve disposed in susbtantially concentric spaced apart relation to said other end of the tube, the ball projecting slightly beyond the end of the sleeve, and a matrix of paper fibers supported in the space between the tube and the sleeve.

2. A writing stylus for a mechanically operated writing device comprising a ball, an axially bored ball support tube, the bore at one end of the tube defining a circular recess of diameter slightly greater than the ball in which the ball is disposed and from which the ball projects to contact a writing surface, a cylindrical sleeve disposed concentric to the tube in spaced apart relation thereto, one end of the slee/e surrounding the ball with the ball projecting slightly beyond the end of the sleeve, and a -matrix of paper fibers supported in the space between the tube and the sleeve.

3. A Writing stylus for a mechanically operated writing device comprising a ball, a support tube having at one end thereof a circular recess of diameter slightly greater than the ball in which the ball is rotatably disposed and from which the ball projects, the end of the tube forming a skirt around the ball for retaining the ball in the recess, a cylindrical sleeve disposed concentric to the tube in spaced apart relation thereto, the sleeve having an end disposed in a plane normal to the elongate extent of the tube adjacent the ball, the ball projecting beyond the plane, and a matrix of paper fibers' supported in the space between the tube and the sleeve.

4. A writing stylus for a mechanically operated writing device comprising a ball, a support tube having at one end thereof a circular recess of diameter slightly greater than the ball in which the ball is rotatably disposed and from which the ball projects, the end of the tube forming a skirt around the ball for retaining the ball in the recess, a cylindrical sleeve disposed concentric to the tube in spaced apart relation thereto, the sleeve having an end disposed in a plane normal to the elongate extent of the tube adjacent the ball, said plane passing between the end of the skirt and the projecting end of the ball, and a matrix of paper fibers supported in and bridging the space between the tube and the sleeve.

5. A writing stylus for a mechanically operated writing device comprising a spherical carbide ball, an axially bored ball support tube adapted to be connected to a source of viscous ink at one end thereof, the bore at the other end of the tube defining a circular recess of diameter slightly greater than the ball, the ball being freely rotatably disposed in the recess and projecting therefrom to beyond said other end of the tube, the tube between said other end and the location of closest radial proximity of the ball to the tube being tapered for retaining the ball in the recess, the tube between said ends having an enlarged diameter portion of circularly cylindrical configuration, a cylindrical sleeve carried by the tube enlarged diameter portion and extending from said enlarged diam-` eter portion to an end adjacent the ball in spaced apart relation to the tube to define an annular gap between the tube and the sleeve, the gap having a dimension radi- `ally of the tube of from .015 to .025 inch inclusive, the ball projecting beyond the end of the tube, and a matrix of paper fibers lodged in the space between the tube and the sleeve around the outer circumference of the tube.

6. A writing stylus for a mechanically operated Writing device comprising a spherical carbide ball, an elongated axially bored ball support tube adapted to be connected to a source of viscous ink at one end thereof, the bore at the other end of the tube defining a circular recess of diameter slightly greater than the ball, the ball being freely rotatably disposed in the recess and projecting therefrom to beyond said other end of the tube, said other end of the tube being tapered toward the tube axis for retaining the ball in the recess, the tube between said ends having an enlarged diameter portion of circularly cylindrical configuration, a cylindrical sleeve carried by the tube enlarged diameter portion and extending therefrom to an end adjacent the ball, the tube and the sleeve being spaced apart between the tube enlarged diameter portion and the `sleeve and to define an annular chamber having a radial extent of from .015 to .025 inch inclusive, the sleeve end being disposed in a plane which is normal to the elongate extent of the tube adjacent the ball, the ball projecting beyond said plane a distance of from .O07`to .Q12 inch, inclusive, and a matrix of paper fibers lodged in the space between the tube and the sleeve around the outer circumference of the tube.

3,215,121 5 6 7. A writing stylus for a mechanically operated writing matrix and having a meniscus around said other end of device comprising a ball support tube adapted at one end the tube to the ball. thereof to be coupled to a source of viscous ink, a spherical ball rotatably mounted in the other end of the tube References Cited by the EXamllel' and projecting beyond the tube end, the tube defining an 5 UNITED STATES PATENTS ink duct from the ink source to the surface of the ball,

a sleeve disposed in substantially concentric spaced apart llav; 120 relation to said other end of the tube, the ball projecting slightly beyond the end of the sleeve into contact with a FOREIGN PATENTS sheet of paper across which the stylus moves, a matrix of 10 713 169 8 5 4 Great Britain paper fibers lodged in the space between the tube and the sleeve, and a pool of ink in the space supported by the EUGENE R CAPOZIO, Primary Examiner,

LAWRENCE CHARLES, Examiner. 

1. A WRITING STYLUS FOR A MECHANICALLY OPERATED WRITING DEVICE COMPRISING A BALL SUPPORT TUBE ADAPTED AT ONE END THEREOF TO BE COUPLED TO A SOURCE OF VISCOUS INK, A SPHERICAL BALL ROTATABLY MOUNTED IN THE OTHER END OF THE TUBE AND PROJECTING BEYOND THE TUBE END, THE TUBE DEFINING AN INK DUCT FROM THE INK SOURCE TO THE SURFACE OF THE BALL, A SLEEVE DISPOSED IN SUBSTANTIALLY CONCENTRIC SPACED APART RELATION TO SAID OTHER END OF THE TUBE, THE BALL PROJECTING SLIGHTLY BEYOND THE END OF THE SLEEVE, AND A MATRIX OF PAPER FIBERS SUPPORTED IN THE SPACE BETWEEN THE TUBE AND THE SLEEVE. 